/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Lucene", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

using System;
using System.IO;

namespace DotnetPark.NLucene.Store
{
	internal class FsInputStream : InputStream 
	{
		private class Descriptor : BinaryReader
		{
			public long position;

			public Descriptor(FileInfo file) : base(new FileStream(file.FullName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
			{
			}
		}

		Descriptor file = null;
		bool isClone;

		public FsInputStream(FileInfo path)  
		{
			file = new Descriptor(path);
			length = file.BaseStream.Length;
		}

		///<summary> InputStream methods </summary>
		public override void ReadInternal(byte[] b, int offset, int len)
		{
			lock(file) 
			{
				long position = GetFilePointer();
				if (position != file.position) 
				{
					file.BaseStream.Seek(position, SeekOrigin.Begin);
					file.position = position;
				}
				int total = 0;
				do 
				{
					int i = file.Read(b, offset+total, len-total);
					if (i == -1)
						throw new IOException("read past EOF");
					file.position += i;
					total += i;
				} while (total < len);
			}
		}

		public override void Close() 
		{

			if (!isClone)
				file.Close();
		}

		///<summary> Random-access methods </summary>
		public override void SeekInternal(long position)  
		{
		}

		public override Object Clone() 
		{
			FsInputStream clone = (FsInputStream) this.MemberwiseClone();
			clone.isClone = true;
			return clone;
		}
	}
}
